Exploring Indium-Based Ternary Thiospinel as Conceivable High-Potential Air-Cathode for Rechargeable Zn-Air Batteries

Reversible oxygen reactions in Zn-air batteries require cost-effective and highly-active bifunctional electrocatalysts to substitute traditional noblemetal based catalysts. Herein, a new and promising electrocatalytic material, ternary CoIn2S4 thiospinel, is demonstrated for effectively catalyzing oxygen reduction and oxygen evolution reactions (ORR and OER) with S-doped reduced graphene oxide (S-rGO) as an electronic conductor. Compared with Co9S8/S-rGO (without In doping), the newly developed CoIn2S4/S-rGO reveals superior electrocatalytic properties for the ORR (half-wave potential of 0.83 V) and OER (overpotential of 0.37 V at 10 mA cm(-2)), demonstrating that the introduction of In can promote the reversible oxygen electrode reactions of CoIn2S4. The superior experimentally- observed electrocatalytic properties are corroborated via density function theory investigations. Meanwhile, the synergistic improvements in the bifunctional activities resulting from the combination of CoIn2S4 and S-rGO are also confirmed. As a proof of concept, home-made Zn-air cells are assembled with CoIn2S4/S-rGO as an air-cathode. The developed Zn-air cells exhibit a high peak power density (133 mW cm(-2)) with an energy density of 951 Wh kgZn(-1) and robust cycling stability over 150 cycles for 50 h, exceeding of those commercial Pt/C+ RuO2 which highlights the practical viability of CoIn2S4/S-rGO for rechargeable Zn-air batteries.